Electrode structure and device containing the same



July 26, 1949.v z. J. ATLE ET AL ELECTRODE STRUCTURE AND DEVICE CONTAINING THE SAME` l Filed March l1, 1946 Patented July 267:, 1.949

UNITED STATES PATENT- OFFICE ELEoTRoDE sTRUcTURE AND DEVICE CONTAINING THE SAME l Zed J Atlee, Elmhurst, and William White Lange, Chicago, Ill., assignors to' GeneralY Electric X-Ray Corporation,- Chicagoglll., a` corporation of New York Appncanon March 11, 1946s'ei'aiN. 653,504

device, faording substantially uniform voltage gradient between the anode and cooperating'v cathode electrodes. f

Another importantobject is to provide cooperating anode and cathode electrodes, wherein the anode comprises a sleeve-like anode shell embracing the cathode; 'a further object being to form the cathode as an elongated filament, adapted'for electron emission Vand located substantially along the central 'axis of the anode shell. Another important'object is'to provide protective means for guarding the filament against so-calledV inverse failure, such failure being caused Vby electrical discharge from anode to cathode as `the result of localized anode heat`v ing, field emission of electrons from the anode,l

or gas burst, any of which may cause a sudden reduction in space charge, `vbetween anode and cathode, allowing for the release of stored energy from'the capacitance of the anode-cathode circuit. Such released energy, if focused upon the lament, may rupture it and render the device inoperable, eventhough otherwise in good operating condition. A further important object, therefore, is to provide means, in association with the cathode, to receive and withstand sudden discharges of stored energy, whereby-to protect the electronV emission element of the cathode against rupture or other damage.

Another important object is to provide protective means, of the character mentioned, com' prising a projecting arrester, on the cathode structure, and extending outwardly-of the electron emission element-and toward the anode, whereby any sudden energy release, for any of the causes heretofore mentioned,A may be"re' ceived and absorbed by said arrestor without damage to the electron emission element.

` The foregoing and numerous other important objects, advantages, and inherent functions of'v the invention will become apparent as the same is more fully understood from the following de- Y 9 claims. (o1. 25o-2715) Schden, ,which, taken in vconnection with accompanying drawings, discloses preferred embodiments of the invention.

Referring to the drawings:

l li'g.` 1 is`r a'sectional view taken substantially through ancelectronic' rectier embodying the present invention;

Fig. 2 is a sectional view taken substantially along the line V2--2 in Fig. l;

FigL is a'view in `longitudinal section throughL a modiedjform of anodeV and cathode embodying the present invention; and Y Fig. flA isY a sectional Vview takensubstantially alo'ng the line lL-lrinl Fig. 3; ffTo illustrate the invention, `the drawings show an` electronic device lin theY form of a rectifier-v I I although the several features of the invention are V'not necessarily vrestricted to rectiers, but may be utilized to advantage, generally, in

electronic devices embodying an electron emit-vL ting source or cathode and a cooperating anode' The electron' for receiving emitted electrons. flow device may comprise a sealed envelope I2 of suitable material, such as glass or metal, glass being specifically shown in the drawings. The

envelope I2 contains an anode I3 and a cooper# ating cathode I4. l The envelope I2 may be ar ranged Ain any suitable, convenient or preferred! form, AAsshown in the drawings, it comprises a tubular glass shell having re-entrant necks I5;

I5?, atits opposite ends. The anode I3 and cathode I4, respectively, are supported on the said.'

necksat the opposite ends ofthe envelope. 'I'he necks I5, I5' define openings, which are closed; by generally cupfshaped seal members I6, I6.f made ofsheet metal, and each having an annulary rim I1, l1' making a glass-to-metal seal I8, |82l with the inwardly extending end of the neck I5` or I5 on which it is mounted.

The seal member I 6, at one end of the envelope., carries the anode i3, which may comprise a cylin-l drical shell I9 ofv suitable anode material, preferably a metal ofhigh conductivity and low elec-y tronic emissivity, such asr molybdenum. TheA anodemay be supported on the end seal as by' 'means of a suitable bracket y2l). This bracketv may be of any preferred form. |but,as shown, preferably Vcomprises molybdenum, formed tog, providera plurality o f spaced arms` or. fingers 2l, in position to. engagefthe outer surfaces of the f shell I9. Thev arms 2| may be interconnected,l

as on a mountingring 22, which maybe secured on theend seal member I6 in any suitable or convenient fashiomto support the shell I 9 preferably, in concentric alinement within the envelope I2.:

To this end, the seal member I6 may be formed with an openingI for receiving a stem 23, having a portion extending outwardly of the end of the envelope and a portion extending inwardly of the envelope through the opening in the seal, said stem being sealed in said opening, and the ring 22 being secured upon the inwardly extending end of the stem in any suitable or preferred fashion, as by means of a holding member 24.

The shell I9 is preferably provided with a pair of spaced apart, outwardly pressed, circumferential ribs 25, which engage the arms 2| of the mounting bracket, the shell being 'secured to said arms in any suitable fashion, and preferably by means of rivets extending through the arms 'and through the shell at the ribs,25. A collar 25 may be, and preferably is, applied at each end of the shell I9, said collars comprising cylindrical rings of tantalum, columbium, zirconium, or other metal, the same preferably comprisingmetal havifngthe ability to absorb gas 'when heated, and thus to perform a getterin'g function within the envelope of the device. These rings may be welded or riveted or otherwise attached to the ends of the shell, and preferably have portions extending beyond, aiid snugly curled about, lthe opposed end edges of the shell I9 'to provide wellrunded beads at the opposite ends of the anode shell. The provision of such 'well-'rounded beads serves to improve voltage 'eld characteristics at the opposite ends of the anode shell; and by making said end pieces of Agette'ring material, such as tantalum, columbiuin, or zirconium, Athe saine may serve, continuously during the service life of the device, to absorb any gaseous impurities which may be released within the envelope, including occluded gases that may be contained in the anode, the cathode, and the material of the envelope itself, andgradually evolved therefrom and released within the envelope during the operation of the device.

The anode thus is mounted on the end seal I at one end of the envelope, the Acathode I4 being preferably supported on the end seal at the opposite end of the envelope. The cathode, as shown, may comprise an electron emission element 21 in position within and surrounded by the anode shell |9, which is preferably cylindrical. The electron emission element may comprise an elongated filament supported in position concerntrically within and preferably axially of theV sleeve I9. The emission lament 21 preferably comprises tungsten wire, the same being supported in place on a suitable mounting structure carried by the end seal. This mounting structure may include a disk-like head 230i metal mounted on the end seal member 1', as by means of a stud 29 which extends through, and is sealed in, an opening formed in the seal member. The stud 29 may have portions extending out- Wardly of the envelope and another portion ex tending inwardly thereof, the member 28 being secured on the said inwardly extending portions of the stud. The head may carry a tubular skirt 3D, secured, at one end, to the periphery of the disklike head 28 and extending thence in position enclosing the glassetometal seal I8. l'l'.he skirt thus encloses a space between the Vseal inem-r ber I6' and the head '28, which space is in open communication with the interior of the envelope through the annular space defined 'by 'the end of the Yskirt 30 and the glass-to-'metal 'seal 18 it encloses. Within the space, thus enclosed, ea'hs may B provided pefh a initial gettering operation, during the manufacture of the device, and, if desired, periodically during the life of the device, in order to insure the maintenance of a high degree of vacuum within the envelope |2, as taught in United States Letters Patent No. 2,260,927, issued to Zed J. Atlee on October 28, 1941.

fIhe opposite ends of the filament 21 are mounted on, electrically connected with, and supported by conductor stems 3| and 32, which are supported on, and electrically insulated from, the head 28, through which they extend, by means of grommets 33 sealed in openings in the head, the stems 3| and 32 extending through the grommets and being supported therein, and insulated therefrom, as by means of glass beads 34 sealed in the grommets around the stems. The end of the stems 3| and 32 may be electrically connected with conductor means 35, 36 extending outwardly of the envelope through sealed grommet means 31 formed in the seal member I6.

If desired, one of the stems, such as the stem 3|, may be rigidly attached to and grounded on the head 28, and need -not extend outwardly of the envelope, electrical connection of the stem 3| with external circuits, in such case, being accomplished through the stern 29. It is desirablel however, to provide an insulated conductor, such as the'conductor 36, for connecting the stem 32 in an external circuit.

The lanient 21 is thus electrically connected outwardly of the envelope, and may be energized for VVelectron emission from an external source of energizing power. One of the support conductors is preferably formed to provide spaced apart loops 3sat intervals in position encircling the emission filament 21, in order to shield the filament against mechanical displacement thereof under the influence of electrostatic stress fields that may be set up between thevlament and the surrounding anode shell I9, as a result of the high operating potential applied therebetween 'when the device is in operation. Such electrostatic fields may exert a mechanical effect upon the relatively weak filament 21 and pull it out of position laterally, unless shielding means, such as the loops 33, are provided. The support conductors 3| and 32, as shown, are .preferably arranged with their ends in spaced apart ali'iieinent on the central axis of the anode sleeve, the filament 21 extending therebetween and being electrically and mechanically attached, at the opposite ends of the filament, to said'spaced, alined ends of the support conductors. In order to insure against damage or destruction of the emission element 21 as a result of electrical discharge or dash-over from the anode to the emission element, ash arresting means is provided in the form of a flashreceiving member or members, disposed preferably at the opposite ends of the emission element and electrically connected to drain olf the flash energy, in harmless fashion, from the vicinity of the emission element. To this end, the flash receiving means may comprise a disk 39, as shownin Fig. 1, or a plurality -of disks 39, as shown in Fig.` 3, mounted on and electrically connected to one or other, or both, of the support conductors 3| and 32, in position at either or both ends of the emission element, and extending outwardly thereof toward the anode sleeve. As shown, the disks are electrically connected on, and supported by, the conductor 32, although it will be obvious that one of the disks could be mounted one, and electrically connected with, the conductor 3|. The disks 39, also, 'may be formedvvith central openings 40 for amano receivingthe lamentfconnected' ends lof the ,conductors 3| and 32. If desired, the anode sleevev aord positive assurance against the occurrence' of any inverse- 'discharge' directly onto vthe emission filament. While the support conductors 3l andSZQthe anode sleeve I9,"'a'n'd the arrestor disks maygbemade of any suitable'or convenient materi'al, it is pref erable'that these elementsbe. made of ,n ietal A'havingl low "electron emissivity; and, consequentlyy, fit" is preferable that thel lahode sleeve,the support conductors,,thedislra and also the ribs lil 'where' used,A be'made of molybdenum, which is a metal having low electron emission characteristics, although tungsten, and other suitable metals, may, of course, be employed.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacricing any of its attendant advantages, the form herein disclosed being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. An electron now device, comprising a sleevelike anode and a cooperating cathode, including an electron emission element, mounted within and co-aXially of said anode, support stems on which said element is mounted and between which it extends, ash arrestor means comprising a member on one of said support stems and extending outwardly of said element toward the anode to receive inverse anode discharge on said member, and means forming a discharge bead on said anode in registering alinement with said ash arrestor means.

2. An electron now device, comprising a sleevelike anode and a cooperating cathode, including an electron emission element, mounted within and co-axially of said anode, mounting means comprising support stems carrying said emission element in position therebetween and electrically connected therewith at the opposite ends of the element, and inverse flash arrestor means comprising members carried by said mounting means in position at the opposite ends of said emission element, said members having portions extending outwardly of said emission element toward said anode, to receive inverse anode discharge thereon for the protection -of the emission element.

3. An electron flow device, comprising a sleevelike anode and a cooperating cathode, including an electron emission element, mounted within and coaxially of said anode, and an inverse flash arrestor member of molybdenum mounted adjacent said emission element and having portions extending outwardly thereof toward said anode, to receive inverse anode discharge thereon for the protection of the emission element.

4. An electron flow device, comprising a sleevelike anode and a cooperating cathode, including an electron emission element, mounted within and co-axially of said anode, an inverse flash arrestor member of molybdenum mounted adjacent said emission element and having portions extending outwardly thereof toward said anode, to receive inverse anode discharge thereon for the 6 protection i of I.; the;` emission .l-element; and a Y discharge rib of molybdenum on said anode in registering Aalinement; with said flash arrestormember. 5.,An electronflow device comprising a sleeve- 1 likeA anode` and avcoloperating cathode, having an elongated electron emission. element mounted withinland. co-axially ofI said anode, :including support stems having alinedcmountingfends on which the Vopposite ends of said emission element element extends,.and an inverse flash arrestormeans comprising a plate-likemember supported on one ofwsaid stemsadjacent an end of .said emission` element, said. plate-like member having portions projecting.radially -V`outwardly ofsaid emissionl element end said stems toward said sleevejlilseanede-f0r reeeivine inverse anode, .diS- charge on said plate-like member.

6. An electron ilow device, comprising a sleevelike anode and a cooperating cathode, having an elongated electron emission element, mounted within and co-axially of said anode, including support stems having alined mounting ends on which the opposite ends of said emission element are electrically connected and between which said element extends, one of said stems forming spaced loops encircling said element between the stem mounted ends thereof, and extending thence in spaced apart, side-by-side relationship with respect to the other stem, whereby both stems may be mounted on a common support spaced from an end of said emission element, and an inverse ash arrestor means comprising a platelike member supported on said stem forming the said looped portions, said plate-like member having portions projecting radially outwardly of said emission element and said stem on which mounted toward said sleeve-like anode for receiving inverse anode discharge on said platelike member.

7. An electron ilow device, comprising a sleevelike anode and a cooperating cathode, having an elongated electron emission element, mounted within and co-axially of said anode, including support stems having alined mounting ends on which the opposite ends of said emission element are electrically connected and between which said element extends, one of said stems forming spaced loops encircling said element between the stem mounted ends thereof, and inverse flash arrestor means comprising platelike members mounted on and electrically connected with said support means, at the opposite ends of said emission element, said arrestor means having portions projecting outwardly of said emission element toward said sleevelike anode for receiving inverse anode discharge thereon.

8. An electron flow device, comprising a sleevelike anode and a cooperating cathode, having an elongated electron emission element, mounted within and co-axially of said anode, including support stems having alined mounting ends on which the opposite endsfof said emission element are electrically connected and between which said element extends, one of said stems forming spaced loops encircling said element between the stem mounted ends thereof, and inverse flash arrestor means comprising platelike members mounted on and electrically connected with said support means, at the opposite ends of said emission element, said arrestor means having portions projecting outwardly of said emission element toward said sleevelike anode for receiving inverse anode discharge thereon, and riblike projections on and extending inwardly of said sleevelike menne anode in'. position regisrin'grwith sind pmbeike members. Y

9. An electron new device, comprising asleeve'- like anode and a cooperating: eathodeg incmding an electron emission eement, mounted. within. andv coaxallyof said anode, support stems on which. said elementi is mounted and eeetriczdtyv connected, at its opposite ends, and. between which it extends, one osaid stemhving portions extending radially outwardy f and alongside said emissienelement, 'anni' mash arrester means .comprising a, disk mounted on a.y Said sulfiport stemand eectrically connected therewith at a mounting point radialy outwardy of said emissien element, said disk being stumm-tedv in ceaxil aiinement with said emission eem'en and extending radiaiiy -outwardy thereof towerd the ,Lebrun Sept. 1, m42 

